1. Field of the Invention
This invention generally relates to load balancing systems and in particular to network based load balancing systems of medical image data.
2. Description of Related Art
Medical diagnostic imaging allows radiologists to perform diagnosis of many types of injury and disease by imaging various internal body parts. For example, radiologists utilize diagnostic imaging to visualize organs in the abdomen, the chest cavity, the brain and central nervous system, and the musculoskeletal system. Diagnostic imaging may be used to detect potential cancer abnormalities; bone densitometry; joint, bone, or soft tissue injuries; and many types of diseases. Presently, diagnostic imaging includes many different types of imaging technologies such as x-rays, ultrasound, computed tomography, magnetic resonance imaging, and nuclear medicine to name but a few.
Traditionally, almost all diagnostic imaging was film based. An image was recorded on a physical piece of film that had to be developed, provided to the physician for viewing, reviewed by the physician, and recorded and stored in an archive. Often there was a significant time delay between the taking of the image and the physician reviewing the image. In addition, the storage of film images required a large physical space and associated record keeping. If a physician needed to refer to a patient's stored records, the film images needed to be physically found, retrieved, and provided to the physician. Often there was a significant time delay in this process as well.
To address these issues, diagnostic imaging technology has advanced and medical diagnostic imaging has shifted from a film based system, to a digitally based system in which diagnostic images are recorded, transferred, viewed, and stored electronically. A hard copy or print out of a diagnostic image may never need to be made. However, the storage of radiological images in digital format is a non-trivial problem due to the very large volume of data that these images contain. For example, projectional X-ray Images require very high resolution to be clinically acceptable. Such images may be acquired and stored in image matrices of more than 2000 by 2000 pixels, with a dynamic range of 8 to 12 bits per pixel. This represents between 4 and 8 Mbytes per stored image. Digital imaging modalities such as computed tomography or magnetic resonance imaging currently generate images with smaller matrices (typically 256×256 or 512×512 with a dynamic range of 12 to 16 Bits per pixel), but generate very large numbers of images during each diagnostic examination that are then combined to form a three-dimensional volume image. Indeed, one examination can generate as few as twenty to in excess of more than one hundred images. This corresponds to storage requirements between 10 and 700 MBytes per diagnostic imaging event. Thus, the electronic database, storage, processing and network resources that are necessary to store, retrieve, transmit, and render a diagnostic image must be capable of handling large size files efficiently and quickly.
One image archiving system that has been developed to store and catalog the medical image files is generally referred to as a Picture Archive and Communication System (PACS). A PACS provides an integrated system that receives image data from one or more imaging modalities, processes the image data as needed, stores the image data within a database, retrieves the data when required, and serves the data to be displayed for review by the physician or a technician. However, because all images and most image based transactions are either processed or passed through the PACS, it often acts as a bottle neck to the flow of image data within the network.